It's usually the stuff of fiction found buried inside fantasy novels or big-budget sci-fi films.
But claims of time travel are become more and more regular - and people are unearthing more 'proof' that the hands of time are being twisted and turned in all directions.
Digging up some photos and artwork from the past, the number of believers appear to be growing by the day.
Conspiracy fans are convinced people have been going back to the future - and they say the evidence is starting to stack up!
Here's some of the photos that have been causing a stir and gives a little credibility to the theories that movement between certain points in time is possible.
Calling time on the doubters!
Many are convinced that a mural from the 1930s proves that time travel really does exist - after spotting a 'mobile phone' in the painting.
The artwork, titled Mr. Pynchon and the Settling of Springfield, was created by Italian artist Umberto Romano in 1937 and depicts the arrival of settlers to the town in the 1620s.
In the scene, a Native American local is holding up a small, black rectangular object similar to the shape of an iPhone and looking directly at it, almost as if he was snapping a selfie.
The peculiar object has left viewers baffled, with many drawing the conclusion that it could be a sign of time travel as iPhones were not invented until 2007.
Is that you, Greta?
There's a lot she can do, like shaping minds across the world when it comes to the evils of climate change.
But can Greta Thunberg go back 120-years and a plant herself among three children working at a gold mine in Canada 's Yukon territory?
People aren't ruling it out!
The picture of "Greta" has taken the internet by storm after social media users were convinced the age-old snap of a woman mining in a field is actually the Swedish activist.
Beach bewilderment
Even an image of hundreds of Brits getting away from the trauma of World War II caused time traveller debate.
An historic picture showed families relaxing on the sands in Cornwall back in 1943.
Yet there is an apparent imposter on the crowded beach which social media users claim doesn't fit.
The brown-suited man, who is standing, can be seen looking at an object in his hand which appears to be a modern-day electronic device.
Unsurprisingly, the suggestions were laughed off by others, who insisted he was just well dressed and rolling a cigarette.
'Hipster time traveller'
Back in 2010 a 'hipster time traveller' was spotted in an intriguing crowd photograph from the 1940s.
The picture in question was taken in 1941 at the reopening of the South Fork Bridge in Canada.
A crowd is stood watching the reopening with one man that stands out due to his clothing and accessories that seem far too modern for the time.
He is sporting a dark t-shirt, sunglasses and a hooded zip jumper while holding a small portable camera and those around him are wearing tailored suits which were in fashion at the time.
The man can be seen wearing a printed T-shirt which bares the letter 'M' underneath a hooded jumper as well as trendy sunglasses.
Apple in the art
Mobile phones being seen before their time is not a new thing.
But art lovers believe they may have found an iPhone in a 350-year-old painting!
The picture, the work of Dutch painter Pieter de Hooch showing a quaint domestic scene, is so convincing even Apple's CEO seemingly thinks it shows one of his company's models.
It can be seen in the hands of a man standing to the right of the picture, according to conspiracy theorists. He is holding a small object, while a couple of women and dogs look on.
Apple boss Tim Cook said: "I always thought I knew when the iPhone was invented, but now I’m not so sure anymore."
